This invention relates to a new method for improving the surface of thermoplastic materials, particularly plastic films. Thermoplastics are often used for such various applications as print-lamination, capacitor, printing, free-albums, metallizing, drawing, magnetic film base and optical application. But the stretched thermoplastics are not really suitable for the above applications because of their too smooth surfaces.
In order to improve the surface characteristics of stretched thermoplastics, various methods have been tried. Physical methods, such as scratching, sand-blasting and roll-embossing have been tried. Also, chemical etching has been tried. But these prior art methods have the disadvantage that the methods require so much labor cost and equipment expenses, because of the necessity of the surface-improvement processes besides film manufacturing line. Moreover, these prior art methods are not effective for all applications because they cannot control the level of the surface-improvement. As a consequence, the desired method has not been established yet.